A Powerful Turn‐On Fluorescent Probe for Phosgene: A Primary Amide Strategically Attached to an Anthracene Fluorophore

Abstract

We report here the application of a robust, selective primary amide moiety appended to a fluorescence signalling entity‐ anthracene, the sensing platform, 9‐AM with a view to fluorescent chemosensing of hazardous phosgene gas. The impressively fast (reaction time<1.5 min) detection of phosgene was achieved through the dehydration of the primary amide functionality to a nitrile group. A low detection limit of 5.56 nm ensures applicability of the probe for sensing of minute levels of phosgene well below prescribed safe limits. In addition, TLC sticks impregnated with the probe function as efficient gas phase phosgene sensors with real‐time applicability.

Fluorescent probes for the detection of chemical warfare agents

“…Similarly, Gangopadhyay et al functionalized anthracene with a primary amide to afford the fluorescent probe 9-AM (193). 195 The phosgene-mediated conversion of the primary amide to nitrile was rapid (o1.5 min) and afforded a substantial increase in fluorescence emission intensity at 440 nm.…”

A Rapid, Highly Sensitive and Selective Phosgene Sensor Based on 5,6‐Pinenepyridine

“…The main colorimetric and fluorescent sensing reactions for phosgene detection are using 1,2‐diamine type compounds in which the acylation of one amino group by phosgene and subsequent intramolecular nucleophilic attack of the second amino group lead to the formation of cyclic urea‐derivatives, resulting in an off‐on response (Scheme 1 ). [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ] The fluorophores are usually BODIPY,[ 20 , 21 , 22 , 23 , 24 ] coumarins,[ 25 , 26 ] 1,8‐naphthalimide,[ 17 , 27 , 28 ] anthracene carboxyimide,[ 29 , 30 , 31 ] 2‐(2’‐hydroxyphenyl)benzothiazole (HBT) [32] or rhodamine. [12] The response rates and sensitivity of these sensors are very diverse and can be significantly slowed down due to the inactivation of the second amino group once the first one undergoes electrophilic attack from the phosgene.…”

Sensitive and Visual Detection of Phosgene by a TICT‐Based BODIPY Dye with 8‐(o‐Hydroxy)aniline as the Active Site

“…Due to their low cost, specificity, high sensitivity, and ease of use, many fluorescent probes for phosgene have been reported [5] with two nucleophilic groups as the active site for the reaction, o ‐diamine (including one amine plus one o ‐aromatic nitrogen), [6a–y] one amine plus one o ‐hydroxy group, [7a–c] o ‐dihydroxy [8] group and others, [9a–l] and summarized in Table S1 in the Supporting Information. Among the largest class of probes, with o ‐phenylenediamine as the active site, would produce a similar fluorescence response to nitric oxide (NO), [6e, f] which induces o ‐phenylenediamine to form benzotriazole [10] …”